Fourier transform infrared (FTIR) spectroscopy monitoring techniques have been discussed, for example in Bornstein et al. U.S. Pat. No. 5,070,243, and Bornstein and Lowry U.S. Pat. No. 5,436,454. In the U.S. Pat. No. 5,070,243 Bornstein et al. claim unclad optical waveguides as probes for fluid medium to increase the sensitivity of spectroscopic measurements by the ATR method. However, the sensors and waveguides claimed are not suitable for tissue diagnostics in vivo. In the U.S. Pat. No. 5,436,454 (1995) Bornstein and Lowry describe another optical probe for remote attenuated total reflectance measurements of liquid, and/or relatively solid materials. Their fiber probes are quite rigid and are characterized by a waveguide element in the form of a loop. In addition, chalcogenide glass is used as the fiber material. These suggested probes are not very practicable for nontoxic, noninvasive tissue diagnostics in vivo. Furthermore the epoxy used for material sealing and the chalcogenide glass as a fiber probe may be toxic and therefore not suitable for tissue diagnostics in vivo. Stevenson et al., in U.S. Pat. No. 5,585,634 (1996) claims attenuated total reflectance sensing with U shaped probes consisting of optical fibers with core cladding, where only the U shaped sensor surface portion is uncladded. This method is limited by the selection of fiber material (chalcogenide glass) and the complex shape of the fiber probe, and requires extended sensing time. In addition, Stevenson does not claim any tissue applications in vivo.
Weissman et al., U.S. Pat. No. 5,569,923 discloses a fiber optic reflectance probe for the FTIR and ATR regime. The probe is made of chalcogenide glass and has not been optimized for tissue diagnostics in vivo. Devices and methods for optical and spectroscopic methods for tissue diagnostics or analysis of biological materials are described in U.S. Pat. Nos. 5,280,788, and 5,349,954. In particular the invention of James et al. U.S. Pat. No. 5,280,788 relates to optical spectroscopy in the diagnosis of tissue where a needle probe is in close contact with the tissue surface. However this method utilizes dye lasers as a light source and is therefore not very convenient for clinical applications. The U.S. Pat. No. 5,349,954 by Tiemann et al. proposes an instrument for characterizing tumor tissue, specifically mammographically abnormal tissue, with a broad band light source and monochromator. This cancer diagnostic technique uses a hollow needle, fiber optic illuminator for breast tissue detection. This method can only analyze shifts in hemoglobin oxygenation. Evans suggests in U.S. Pat. No. 5,419,321 a non-invasive medical sensor for living tissue such as skin tissue or organs, where the noninvasive monitoring process is not specified in detail. This patent is based on the non-invasive determination of analyte concentration in the bodies of mammals, in particular the concentration of glucose in blood. Stoddart and Lewis in U.S. Pat. No. 5,349,961 disclose a methodology and apparatus for the clinical evaluation of biological matter, related to internal tissue characterization of skin pigmentation, on a nonintrusive in vivo basis. The examination and/or analysis of tissue and/or biological materials is performed by optical spectrometry in the visible and near infrared range, which do not provide molecular vibrational band information.